1. Field of the Invention
This invention relates to a digital broadcasting reception system comprising a receiver for receiving signals transmitted by digital broadcasting, a display for displaying the images and/or the sounds of the signals transmitted by digital broadcasting and received by the receiver and a printer for printing any of the images of the received signals. The present invention also relates to a digital broadcasting receiver comprising a printing section for printing any of the images of the signals transmitted by digital broadcasting and received by the receiver. Furthermore, the present invention also relates to a receiver for receiving signals transmitted by digital broadcasting and a printer adapted to print any of the images of the signals transmitted by digital broadcasting and received by the receiver. Finally, this invention also relates to a printing method to be used for printing images of signals transmitted by digital broadcasting by means of a printer according to the invention.
2. Related Background Art
Conventionally, an analog video printer is used for printing out any of the images of the reception signals displayed on a display, which may typically be a CRT (Cathode Ray Tube) display.
FIG. 1 of the accompanying drawings is a schematic block diagram of a known analog video printer. Referring to FIG. 1, analog video signals output from display 500 are input to the printer. In the case of FIG. 1, the display 500 is adapted to receive television signals and video signals and display images produced out of the received signal. An analog video printer 501 is adapted to receive analog video signals representing images displayed on the display 500.
The analog video printer 501 performs an digitizing processing operation on the input analog video signal and stores it in frame memory 502 as video data to update the data already stored in the frame memory 502. Upon receiving an external command for printing one or more than one images, the analog video printer 501 suspends the operation of storing data and updating the data in the frame memory 502 and reads out the video data stored in the frame memory 502 in order to print the images by means of printer engine 503.
The analog video printer 501 is provided with a printing confirmation display section 504 which is typically a liquid crystal display for confirming the video data to be used for the printing and analogizes the stored and updated video data in frame memory 502 into an analog video signal, which is then output to the printing confirmation display section 504. The printing confirmation display section 504 displays the image generated from the input analog video signal.
An analog video printer 501 having a configuration as described is norm ally used to print a specific image contained in a continuous moving picture data. Therefore, the external printing command is a two step command including a first step of confirming the image selected out of the moving picture data and a second step of initiating the operation of printing the confirmed image. While the analog video printer 501 may not be provided with a printing confirmation display section 504, then it is not possible to confirm in advance the image to be printed.
The above described analog video printer 501 is adapted to use generally available signals such as NTSC (National Television System Committee) signals, PAL (Phase Alternation by Line) signals, RGB video signals and S terminal video signals.
Analog multi-scan printers and PC printers normally are used for printing out images displayed on the displays of information processing apparatus such as personal computers (to be referred to as PCs hereinafter).
As shown in FIG. 2 of the accompanying drawings, an analog multi-scan printer 510 is typically adapted to receive an analog CRT interface signal output from the PC main frame 511 to the display 512. The analog multi-scan printer 510 duplicates the input analog CRT interface signal and outputs one of the signals to display 512, while performs a processing operation of digitizing the other signal. The digitized signal is then sent to the frame memory 513 as video data to be recorded there in order to update the data already stored there. Then, upon receiving an external printing command input to it, it suspends the operation of storing data and updating the data in the frame memo 513 and reads out the video data stored in the frame memory 513 in order to print the images by means of printer engine 514.
Alternatively, an analog multi-scan printer 510 may comprise a printing confirmation display section just like the above described analog video printer 501. The analog CRT interface signal may be an RGB video signal and a synchronizing signal to be used for the RGB video signal. The signal mode of analog CRT interface signals is usually defined by the following values:                horizontal resolution: 640-1600 dots,        vertical resolution: 480-1200 lines,        horizontal deflection frequency: 30-107 kHz and        vertical deflection frequency: 48-160 Hz.        
An analog multi-scan printer 510 is adapted to operate for multi-scanning according to a signal of the above signal mode and obtain video data good for the size of the picture to be printed for the purpose of printing.
FIG. 3 of the accompanying drawings is a schematic broadcasting of a PC printer. Referring to FIG. 3, the PC printer 520 is adapted to receive printing data from PC main frame 521 apart from the video signal output from the PC main frame 521 to display 522 by way of general purpose printer interface.
With the PC printer 520, character data and video data are generated by an application program driven by the PC main frame 521 and delivered to the OS (Operating System) of the PC main frame 521 to display images on the display 522. Upon receiving a printing command, the OS causes the printer driver contained in the PC main frame 521 to start operating and then the printer driver converts the character data and the video data into printing data in a format adapted to the PC printer 520 connected to the PC main frame 521 and transmits the printing data to the PC printer 520. Then, the PC printer 520 translates the printing data it receives and operates to print out appropriate images as it is driven to operate by printer engine 523.
The general purpose printer interface of the PC printer 520 may typically be a Bi-Centronics (IEEE-1284), an RS-232C, an SCSI, an Ir-DA or a USB.
When receiving news and programs of television broadcasting, conventionally, analog television signals are received by means of a receiver. The received analog television signal is then processed by an analog electronic circuit to obtain the image represented by the signal, which image is then displayed on a display. However, television broadcasting is expected to replace analog signals with digital signals in near future.
More specifically, in Japan, CS digital broadcasting started in October '96 and it is expected that the current CATV, BS broadcasting and ground wave broadcasting are digitized very soon. Digital television broadcasting can provide higher quality images than analog television broadcasting. Furthermore, digital television broadcasting can additionally provide various information services referred to as SI (Service Information) in addition to the transmission of ordinary television signals. Services such as EPGs (Electronic Program Guides) can be provided by means of SI signals and displayed on displays.
Thus, with digital television broadcasting, it is possible to display not only news and programs but also various program guides simultaneously or selectively. Then, the television display set is required to display high definition images in terms of not only pictures but also characters. Additionally, the receiver set is required to process various digital signals it receives and send the processed digital signals to the display set.
Meanwhile, in recent years, various organizations have been studying about digital interface standards to be established for displays that are adapted to be connected to the video ports of various electronic devices such as personal computers and set top boxes (to be referred to as STB hereinafter). For instance, the Japan Electronic Industry Development Association (JEIDA) has already established the Digital Interface Standards for Monitor, Version 1.0 in January '99.
Under these circumstances, conventional analog video printers 501, analog multi-scan printers 510 and PC printers 520 as described above give rise to a number of problems particularly in terms of printing quality, printing rate and the cost of printer when they are used for printing pictures and service information provided by digital television broadcasting.
More specifically, the analog video printer has to use analog video signals 501 such as NTSC signals. The number of dots that an analog video signal can provides for an image is 600 dots×450 dots at most. Additionally, analog video signals faces a limit in terms of high definition when providing color information for moving images, although this may not be any problem for viewers seeing them on the television screen because of the perceptual characteristics of the visual sense of man. Still additionally, analog video signals are limited in terms of the length of the signal line that can be used for sending them from the display to the printer. In other words, it is difficult to arrange the display and the printer remotely relative to each other.
On the other hand, the analog multi-scan printer can obtain video information up to 1600 dots×1200 dots per image depending on the signal mode to be used. However, on characteristics of the analog CRT interface signal, the analog video printer 501 also faces a limit in terms of the length of the signal line that can be used for sending video signals from the display to the printer. Additionally, the analog multi-scan printer 510 requires circuits for A/D conversion and D/A conversion along with measures for preventing noises and degradation of signals, which make the printer very complex and costly.
The PC printer 520 can transmit video data almost without limitations in terms of resolution and quality of printed images because the general purpose printer interface can cope with high speed operations. However, most of the operation of processing images necessary for the printer engine 523 of the PC printer 520 for printing has to be carried out by the PC main frame 521. Then, the RAM and the hard disk memory of the PC main frame 521 are required to have a large memory capacity in order to make themselves adapted to high resolution and high quality printing. Additionally, the PC main frame 521 has to be provided with a CPU that can operates at high speed in order to process video data at a rate corresponding to the resolution and the quality of the images to be printed. Still additionally, the PC main frame 521 has to be provided with an operational environment good for such high speed operations.
Finally, when transmitting video data by connecting a television receiving set for receiving television broadcasting and a printer and using a general purpose printer interface such as the one used for the above described PC printer 520, the television receiving set has to be provided with a high speed arithmetic processing capacity, a large capacity memory means and a high speed output port for the general purpose interface to push up the cost of the television receiving set, although the high speed arithmetic processing capacity, the large capacity memory means and the high speed output port for the general purpose interface remain useless unless a printer is connected to the television receiving set.